Rifles comprising a spring of the type described in EP 0655598 are spring-loaded rifles which unlike those of the PCP (Pre Charged Pneumatic) type do not require an external source of pressurised gas to discharge shot or any kind of munition.
In spring-loaded rifles air is compressed manually by means of a spring. As a consequence, activating the trigger (firing) releases a spring which activates a piston. Rapid movement by the piston causes the air in a container to be compressed. The compressed air present in the container or caused through the action of the piston is subsequently discharged through an opening of diameter smaller than the container, which helps to increase the pressure of the air. Finally the discharged compressed air is used to impel a shot or other type of munition.
The rifles have substantially poorer performance with regard to accuracy than a rifle of the PCP type. The main difference in performance is due to the need for parts to move during firing, which causes vibration and recoil. Nevertheless spring-loaded rifles are an important option because of their low cost and their need for few additional accessories, such as pre-compressed gas cylinders, among others.
At the present time spring-loaded rifles are mechanically fired by means of a trigger and a counter-ratchet which are released through the action of the trigger, allowing the air compressed by the spring to pass through the barrel.
In order to improve accuracy it is necessary for the user's action on the trigger to require the least force possible, given that action of greater force on the trigger causes undesirable movement of the rifle at the time of firing. Thus at the present time the connection between the trigger and the counter-ratchet has an area of contact which is as small as possible. This ensures that the required movement to release the counter-ratchet and therefore to fire is small, requiring less force to activate it.
This type of mechanism to reduce the amount of force necessary to activate firing has the result that when the contact surfaces are very small, any force applied externally, for example by an impact, even if not directly acting on the trigger, causes the trigger and the counter-ratchet to disengage, activating undesired firing. Hence the need to have the smoothest possible firing in a weapon which passes safety tests such as for example that known as the drop test. This test comprises dropping the weapon freely in all possible positions of the rifle, and the test is passed if the rifle does not fire in any position.
According to this invention an electronic firing mechanism may be incorporated so that the least force possible is used and a contact surface between the trigger and counter-ratchet which guarantees safety is maintained. Through the use of a firing mechanism of this type there is no need to overcome the friction force between the two surfaces, given that the system of operation is different, as only the force necessary to activate a switch is used. The trigger and counter-ratchet are preferably disconnected through an internal mechanism through the action of a solenoid, but any other electromechanical firing mechanism may be used.